linux-kernel - Re: [PATCH v2 2/2] spi: add driver for NXP XSPI controller

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Message-ID: <aRtao9FoPug78T93@sirena.co.uk>
Date: Mon, 17 Nov 2025 17:25:55 +0000
From: Mark Brown <broonie@...nel.org>
To: Haibo Chen <haibo.chen@....com>
Cc: Han Xu <han.xu@....com>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, linux-spi@...r.kernel.org,
	imx@...ts.linux.dev, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] spi: add driver for NXP XSPI controller

On Mon, Nov 17, 2025 at 07:04:25PM +0800, Haibo Chen wrote:

> Add driver support for NXP XSPI controller.
> 
> XSPI is a flexsible SPI host controller which supports up to
> 2 external devices (2 CS). It support Single/Dual/Quad/Octal
> mode data transfer.

This looks pretty good, a couple of small points:

> +static irqreturn_t nxp_xspi_irq_handler(int irq, void *dev_id)
> +{
> +	struct nxp_xspi *xspi = dev_id;
> +	u32 reg;
> +
> +	/* Clear interrupt */
> +	reg = readl(xspi->iobase + XSPI_FR);
> +	writel(XSPI_FR_TFF, xspi->iobase + XSPI_FR);
> +
> +	if (reg & XSPI_FR_TFF)
> +		complete(&xspi->c);
> +
> +	return IRQ_HANDLED;
> +}

This just unconditionally acks interrupts without checking if there was
actually anything there - that means that if some design shares the
interrupt or it spuriously fires then the interrupt core won't handle
things properly.  The driver should really return IRQ_NONE if there is
no interrupt pending.

> +		WARN_ON(!(reg & XSPI_FR_TBFF));
> +		if (i == ALIGN_DOWN(op->data.nbytes, 4)) {
> +			/* Use 0xFF for extra bytes */
> +			left = 0xFFFFFFFF;
> +			/* The last 1 to 3 bytes */
> +			memcpy((u8 *)&left, buf + i, op->data.nbytes - i);
> +			writel(left, base + XSPI_TBDR);
> +		} else
> +			writel(*(u32 *)(buf + i), base + XSPI_TBDR);

If one side of the if has { } they both should.

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